Spinal Myxopapillary Ependymoma

Spinal myxopapillary ependymomas are a variant type of spinal ependymoma that occur exclusively in the conus medullaris and filum terminale. They represent 13% of all spinal ependymomas and are by far the most common tumours of the conus medullaris and filum terminale.

Clinical presentation

The most common presenting symptoms are low back, leg or sacral pain. Up to 25% of patients may present with leg weakness or sphincter dysfunction.

They may occasionally present as a subarachnoid haemorrhage.

Radiographic features

Plain film/CT

If they become large, myxopapillary ependymomas may expand the spinal canal, cause scalloping of the vertebral bodies and extend out of the neural exit foramina.

MRI

Smaller tumours tend to displace the nerve roots of the cauda equina; larger tumours often compress or encase them 8.

Reported signal characteristics include:

T1

usually isointense

prominent mucinous component occasionally results in T1 hyperintensity

haemorrhage and calcification can also lead to regions of hyper- or hypointensity

T2

overall high intensity

low intensity may be seen at the tumour margins because of haemorrhage (myxopapillary ependymomas are the subtype of ependymomas that are most prone to haemorrhage 8)

calcification may also lead to regions of low T2 signal

T1 C+ (Gd)

enhancement is virtually always seen

the enhancement pattern is typically homogeneous, however they can have a variable enhancement pattern that, in part, depends on the amount of haemorrhage present

Differential Diagnosis

Differential diagnosis of a small conus and filum terminale myxopapillary ependymoma includes:

• spinal schwannoma (often indistinguishable from ependymoma)
• spinal paraganglioma

differential diagnosis of a large myxopapillary ependymoma that causes sacral destruction:

• aneurysmal bone cyst: involving the spine
• chordoma
• giant cell tumour: involving the spine